For all the current hoopla about web services, the dominant standard in most industries for exchanging business documents electronically is still the pre-Internet e-commerce standard of EDI. Users have made significant investments in EDI software and skills, and they know they can rely on the technology.

The iron and steel industry is no exception. So while European steel industry collaboration hub STEEL24-7 is developing the promise of web services because it is more economical for smaller companies  and facilitates collaborative partnerships that were previously unimaginable  the progression is one of evolution rather than revolution.

"Whether people are using XML or EDI doesn't matter from a business perspective," says Anders Tholen, a consultant with STEEL24-7's customer integration team. "The problems they are solving are the same. They are just two different technologies.

"There are a lot of benefits from XML. One is making things cheaper and more standardised; but it also extends integration possibilities  such as machine-readable business process and message definitions, and collaboration partner profiles  that are not possible in EDI. It will take some time, though, to mature and for adoption to spread."

The recommended path for EDI users embarking on that migration is through adopting the ebXML standard for e-business data, jointly developed by the UN body that oversees EDI and by e-business standards organization OASIS. Because it includes support for EDI in its messaging protocols, ebXML can provide a trusted migration path into XML and web services for conservative users.

As STEEL24-7 has discovered, it can also help plug an embarrassing gap in the web services standards stack, by contributing a mature, vendor-neutral messaging standard that adds security and reliability to the core web services message format of SOAP. "ebXML was the only standard that provides the features we were looking for. There were no alternatives," says Tholen. "Web services bodies are working on reliability and security but the specs are not ready yet and they are not interoperability tested."

EDI investments

STEEL24-7, set up two years ago by European steel giants Arcelor, Corus and ThyssenKrupp Steel, is one of the world's first major production implementations of ebXML. In the long run, buyers and producers will be able to meet, negotiate, buy and sell and maintain their commercial relationships through the STEEL24-7 platform. It aims to bring the benefits of e-business to the entire industry, reducing process costs, improving yield and enabling better use of capital.

But while it looks to the future, a key founding goal of the initiative was to support existing business  and that means EDI. "The fact is that in the steel industry 90 percent of message-based integration is based on EDI presently," explains Tholen, who is employed by Stockholm-based integrator Ferrologic, which has provided much of the expertise for the project. "So integration departments have made large investments in EDI tools and knowledge, and will continue to use EDI for many years. However, migration will gradually take place, both to transport of EDI messages over the Internet and to XML-based messaging."

The key to making the migration as painless as possible for participants was a messaging infrastructure built on ebXML Message Service (ebMS), the messaging transport component of ebXML. Because ebMS can carry messages in any variety of XML, as well as EDI e-commerce documents and even binary data, STEEL24-7 has been able to offer the additional economy and interoperability of an XML-based message architecture, while supporting both EDI and XML message formats. The company has developed a sophisticated translation offering, based on WebMethods technology, which converts messages between the European Confederation of Iron and Steel Industries' (Eurofer's) version of EDIFACT and its XML-based ESIDEL standards.

Translation currently covers order and order response, delivery forecast and despatch advices. "We have decoupled the syntax chosen by each company so buyers and sellers can upgrade to XML, independently," Tholen explains. As Eurofer continues to add new message definitions to the ESIDEL standard, STEEL24-7 subsequently adds these messages to its service offering.

Tholen feels ebMS, which OASIS ratified as a standard in August 2002, will become the prevalent messaging standard for e-business. "We wanted a low-cost solution that was vendor neutral and secure and reliable. So it needed to have non-repudiation, multiple retries, acknowledgement and receipts, etc. Moreover [ebMS] has been interoperability tested by a large range of vendors in both Europe and the US and I believe it will become the given choice for e-business messaging."

Reliability layers

Although STEEL24-7 uses ebMS within an ebXML environment, the messaging standard can also be used independently. Proponents argue that its maturity as a finished specification for high-volume e-business makes it an ideal candidate to rectify the current lack of a standard for reliable messaging in the web services stack, where rival initiatives such as WS-Reliability and WS-ReliableMessaging are still jockeying for position.

"You need several levels of reliability," says Jean-Jacques Dubray, chief architect at Eigner Precision Lifecycle Management, based in Waltham, Massachusetts, whose software enables manufacturers to exchange product engineering data with their designers and component suppliers. "The web services camp does not yet understand these levels of protocols, they only understand transport-level reliability."

Within the multi-layered ebXML standard framework, ebMS forms the transport layer, which fulfils the base-level reliability requirement of ensuring that a message reaches its destination. Other elements of ebXML add further layers of reliability, such as, explains Dubray, confirming that the message was in a valid format and thus intelligible to the receiver ("structural reliability"), and that it was processed without errors ("substantive reliability").

STEEL24-7 adds structural reliability by recording the pre-agreed semantics of interactions between partners in an ebXML format known as a collaboration protocol agreement (CPA). "The collaboration partner profiles describe services provided, such as which messages and business processes are supported, which security and reliability settings are supported and so on," explains Tholen.

Broader appeal

Yet despite all this sophistication, it is the price tag that attracts companies to join STEEL24-7 today, says Tholen, and few have explored the potential to move into new fields such as SOAP web services. "Where we have come in to smaller companies who do not have an integration solution, generally they achieve significant savings with our solutions and this will be the springboard for e-business to happen. For a bigger company, it's an opportunity to set up integration with smaller companies."

Future plans for STEEL24-7 include support for new message types including invoices later in the year. The key benefit will be enhancing the extent to which suppliers and buyers can receive business messages in their own chosen format  whether that be EDI, XML or even viewing a printable form in their web browser.

For STEEL24-7, the main benefit of ebMS is its core role in allowing this flexibility in message formats. But the security and reliability capabilities of ebMS give it a broader appeal that may take it into web services deployments far beyond the community of traditional EDI and ebXML users.

Reliability, as Dubray points out, is a fundamental requirement in any production environment. Citing the example of Magna Steyr, a German automobile supplier that uses Eigner's software to exchange entire vehicle designs and bills of materials with motor manufacturers, he points out just how much can go wrong if the underlying messaging proves unreliable: "You don't want any inconsistency showing up in such a data exchange. It would have a far greater impact than a lost PO, you simply could produce the wrong car!"